How people can drink ocean water, but animals like
fish can not; and how can fish breath ocean water
and drinking it is not healthy for those animals
which live in bad ocean waters? PLEASE WRITE BACK,
thank you, love.

Question Date: 2013-12-29

Answer 1:

It is highly discouraged that you drink ocean
water! Because there can be a lot of salt content
in ocean water, drinking it causes cells in your
body to lose water (the opposite of what drinking
water is supposed to do!). This will lead to
muscle cramps, dry mouth, thirst, and dehydration.
Saltwater fish, on the other hand, have adapted
to keep the water level in their cells level.
Because they live in such salty conditions, fish
constantly lose water and they must drink water
through their mouths and filter out the salt in
their gills. Freshwater fish do not face this
problem and do not have to actively drink water.
Gills on a fish also serve like lungs to absorb
oxygen from the water and release carbon dioxide
back into the water. Fish and other marine
species can be threatened by bad waters. For
instance, an oil spill in the ocean means that
fish will be covered in and ingesting crude oil
from the polluted water. This can restrict their
breathing and poison them in the long run.

Answer 2:

Ocean water is very salty, saltier than our blood.
You can drink a little bit because you can drink a
little salt water; all animals can, in fact. But
drink too much, and you will die, because too much
salt is poisonous (it sucks all of the water out
of you causing you to die of basically thirst).

Most animals that live in the ocean have blood
that is about as salty as the ocean itself, and as
a result they can drink/breathe the water, because
salt only sucks water out if that water is less
salty than itself. Animals that live in fresh
water suffer the same way we do in ocean water;
too much of the water gets sucked out of them and
they die. Again, it depends on the amount of ocean
water.

Answer 3:

Actually, people can't drink ocean water
directly. If you ever tried it, it's not a very
pleasant experience because it is SO salty. In
fact, if you drink a lot of ocean water, the large
amount of salt will actually "dehydrate" you.
Dehydrate means it will absorb the water in your
body and make you MORE thirsty. For people to
drink ocean water, it must first be "desalinated,"
which means that the salt is removed from it at a
water treatment facility.

On the other hand, salt-water fish and other
animals including mammals can usually drink ocean
water, but their bodies have evolved to handle the
large amounts of salt. These animals are able to
get rid of the extra salt through their urine or
through their gills. People are not adapted for
this, so drinking too much salt water could
actually be dangerous to a person's health.

You asked how fish breathe ocean water. Fish
use an organ called their gills to get oxygen from
the water. Fish do not have lungs like people and
ocean mammals do. Dolphins and whales are ocean
mammals (not fish), and they breathe regular air
through their blowholes, which goes to their
lungs. They hold their breath when they are
underwater just like we do, but they can hold
theirs for much longer.

Lastly, you asked about bad ocean waters. I
think you mean ocean waters that are polluted with
chemicals and materials that are not naturally
found in the ocean. This water can be dangerous to
both humans and animals for all purposes including
swimming, bathing or drinking. Pollution of our
oceans is a serious problem and requires
agreements between all countries of the world to
create laws that keep the ocean clean.